Once a connection is made by someone typing in a brand name or other search query and then clicking on a site it creates a connection in Google's eyes. The search engine can then store that info and use it in the context of unlinked mentions around the web in order to help weight rankings of particular sites.

If this is the Panda Patent, as it is part of a wider algorithm, it would also look at the quality of pages on a site and how "commercial" they are in their targeting – this was originally designed to negatively impact content farms that created content targeted aggressively at commercial terms – those that think "search engine-first" as opposed to "audience-first."
Sursa.